Method and apparatus for temporal wavelet compression

1. A method for further compressing a compressed data stream using a temporal wavelet compression unit, the method comprising: in a decompression unit, receiving a data stream that has been compressed using a first compression protocol; in the decompression unit, partially decompressing the data stream using the first compression protocol to obtain wavelet coefficients; in an exclusive-OR comparison unit, reducing temporal redundancy in the data stream using an exclusive-OR comparison protocol on the wavelet coefficients, where the exclusive-OR comparison protocol includes for each frame in the data stream that is not a key frame: determining whether to initialize a frequency band compression threshold, wherein the threshold is to indicate at what point wavelet frequency bands should be skipped, where the skipped frequency bands have already been compressed enough using the first compression protocol; and determining whether a first wavelet frequency band is within the threshold, and if so, performing a mathematical exclusive-OR operation on the wavelet data at a quantized wavelet coefficient layer across the first wavelet frequency band; and in a recompression unit, recompressing the data stream using the first compression protocol.

2. The method as recited in claim 1 , further comprising transmitting the data stream after said recompressing.

3. The method as recited in claim 1 , further comprising storing the data stream after said recompressing.

4. The method as recited in claim 1 , wherein the data stream is received as a compressed signal from a security camera.

5. The method as recited in claim 1 , wherein the first compression protocol includes run-length encoding and entropy encoding of quantized data.

6. The method as recited in claim 5 , wherein the entropy encoding is Huffman encoding.

7. The method as recited in claim 1 , wherein the data stream is received from a compression ASIC.

8. The method as recited in claim 7 , wherein the compression ASIC is an ADV601.

9. The method as recited in claim 1 , wherein the exclusive-OR operation is: qn[x,y,b]=qn[x,y,b]⊕q(n−1)[x,y,b], wherein n is the frame number and q is a quantized wavelet coefficient at a point determined by pixel locations x and y in the wavelet band corresponding to value b.

10. The method as recited in claim 1 , further comprising: determining whether a recompressed data stream resulting from said recompressing is further compressed than the received data stream; and discarding the recompressed data stream if it is not further compressed than the received data stream.

11. An apparatus to further compress a compressed data stream, comprising: means for receiving a data stream that has been compressed using a first compression protocol; means for partially decompressing the data stream using the first compression protocol to obtain wavelet coefficients; means for reducing temporal redundancy in the data stream using an exclusive-OR comparison protocol on the wavelet coefficients, where said means for reducing temporal redundancy includes for each frame in the data stream that is not a key frame: means for determining whether to initialize a frequency band compression threshold, wherein the threshold is to indicate at what point wavelet frequency bands should be skipped, where the skipped frequency bands have already been compressed enough using the first compression protocol; means for determining whether a first wavelet frequency band is within the threshold; and means for performing a mathematical exclusive-OR operation on the wavelet data at a quantized wavelet coefficient layer across the first wavelet frequency band, when the first wavelet frequency band is within the threshold; and means for recompressing the data stream using the first compression protocol.

12. The apparatus as recited in claim 11 , further comprising means for transmitting the data stream after recompressing by said recompressing means.

13. The apparatus as recited in claim 11 , further comprising means for storing the data stream.

14. The apparatus as recited in claim 11 , wherein said receiving means receives the data stream as a compressed signal from a security camera.

15. The apparatus as recited in claim 11 , wherein the first compression protocol includes a run-length encoding and an entropy encoding of quantized data.

16. The apparatus as recited in claim 15 , wherein the entropy encoding is Huffman encoding.

17. The apparatus as recited in claim 11 , wherein the data stream is received from a compression ASIC.

18. The apparatus as recited in claim 17 , wherein the compression ASIC is an ADV601.

19. The apparatus as recited in claim 11 , wherein said means for performing the mathematical exclusive-OR operation comprises: means for calculating qn[x,y,b]=qn[x,y,b]⊕q(n−1)[x,y,b], where n is the frame number, and q is a quantized wavelet coefficient at a point determined by pixel locations x and y in the wavelet band corresponding to value b.

20. The apparatus as recited in claim 11 , further comprising: means for determining whether a recompressed data stream resulting from said recompressing is further compressed than the received data stream; and means for discarding the recompressed data stream if it is not further compressed than the received data stream.

21. An apparatus to further compress a compressed data stream, comprising: a decompression unit to receive and partially decompress the compressed data stream to produce decompressed data of wavelet coefficients; an exclusive-OR comparison unit, coupled to the decompression unit, to perform a mathematical exclusive-OR operation on the decompressed data of wavelet coefficients to reduce temporal redundancy in the compressed data stream, where the exclusive-OR comparison unit, for each frame in the compressed data stream that is not a key frame: determines whether to initialize a frequency band compression threshold, wherein the threshold is to indicate at what point wavelet frequency bands should be skipped, where the skipped frequency bands have already been compressed enough; determines whether a first wavelet frequency band is within the threshold; and when the first wavelet frequency band is within the threshold, performs the mathematical exclusive-OR operation on the wavelet data at a quantized wavelet coefficient layer across the first wavelet frequency band to produce resultant data; and a recompression unit to compress the resultant data to produce a further compressed data stream.

22. The apparatus as recited in claim 21 , wherein said decompression unit comprises: an entropy encoding/decoding unit, to receive the compressed data stream and to decode the compressed data stream to produce decoded data; and a run-length encoding/decoding unit, coupled to said entropy encoding/decoding unit and said exclusive-OR comparison unit, to further decode the decoded data into quantized data supplied to said exclusive-OR comparison unit as the decompressed data.

23. The apparatus as recited in claim 22 , wherein the entropy encoding/decoding unit is a Huffman entropy encoder/decoder.

24. The apparatus as recited in claim 22 , wherein said recompression unit shares said entropy encoding/decoding and run-length encoding/decoding units with said decompression unit by said run-length encoding/decoding unit encoding the resultant data after said exclusive-OR comparison unit processes the quantized data, to produce encoded data, and said entropy encoding/decoding unit compressing the encoded data to produce the further compressed data.

25. The apparatus as recited in claim 21 , wherein said exclusive-OR comparison unit performs the exclusive-OR operation by: calculating qn[x,y,b]=qn[x,y,b]⊕q(n−1)[x,y,b], where n is the frame number, and where q is a quantized wavelet coefficient at a point determined by pixel locations x and y in the wavelet band corresponding to value b.

26. The apparatus as recited in claim 21 , wherein said decompression unit is further coupled to a compression ASIC to receive the compressed data stream.

27. The apparatus as recited in claim 26 , wherein the compression ASIC is an ADV601.

28. The apparatus as recited in claim 21 , further comprising a last frame buffer unit, coupled to said exclusive-OR comparison unit, to store the previous frame data.

29. A system to create and compress video data, comprising: a video unit to create video data; a compression ASIC, coupled to said video camera, to compress the video data using a first compression protocol; a temporal wavelet compression unit, coupled to said compression ASIC, to partially decompress the video data into reconstituted video of wavelet coefficients, to reduce temporal redundancy in the reconstituted video using an exclusive-OR comparison protocol on the wavelet coefficients, where the exclusive-OR comparison protocol includes for each frame in the video data that is not a key frame: determining whether to initialize a frequency band compression threshold, wherein the threshold is to indicate at what point wavelet frequency bands should be skipped, where the skipped frequency bands have already been compressed enough using the first compression protocol; and determining whether a first wavelet frequency band is within the threshold, and if so, performing a mathematical exclusive-OR operation on the wavelet data at a quantized wavelet coefficient layer across the first wavelet frequency band; and the temporal wavelet compression unit to recompress the reconstituted and temporally reduced video using the first compression protocol to produce further compressed video data; and a storage unit, coupled to said temporal wavelet compression unit, to store the further compressed video data.

30. The system as recited in claim 29 , wherein said system is connectable to a network, and wherein said system further comprises a network interface coupled to said storage unit and the network, to transmit the further compressed video data over the network.

31. The system as recited in claim 29 , wherein the first compression protocol includes run-length encoding and entropy encoding of quantized data.

32. The system as recited in claim 31 , wherein the entropy encoding is Huffman encoding.

33. The system as recited in claim 29 , wherein the compression ASIC is an AD V601.